In his geometry class, William took 5 exams. His scores were 87, 77, 75, 95, and 86. What was his average score on the exams?
The average is the sum of his scores divided by the number of scores. There are 5 scores and their sum is $87 + 77 + 75 + 95 + 86 = 420$ His average score is $420 \div 5 = 84$.